1. Field of the Invention
The present invention relates to a method for manufacturing a polishing pad and a polishing pad.
2. Description of the Related Art
Chemical mechanical polishing (CMP) is a procedure for planarizing the surface of a substrate with a polishing pad. CMP is generally applied in polishing lens, mirrors, substrates of liquid crystal displays, silicon wafers, and oxidation and/or metal layers on silicon wafers.
Taking silicon wafers as an example, ingots of monocrystalline silicon are sliced first. The wafers are usually lapped to make them flat for subsequently chemical etching. A polishing process is required after the etching process. During the polishing process, a polishing pad together with slurry reacts chemically with the silicon atoms on the surface of the wafer to make the reacted surface softer than the underlying silicon. Furthermore, the reacted surface is continually wiped away causing fresh silicon to be exposed to the slurry and the polishing pad.
A conventional polishing pad is disclosed in U.S. Pat. No. 6,860,802. A thermosetting mixture is poured into a cylindrical mold. Then, the thermosetting mixture is cured or heated to become a block. The block is cooled and skived into a polishing pad. The thermosetting mixture according to the conventional polishing pad usually has a low solid content, such as about 25 to 35 wt %, so that the thermoset fails to distribute evenly. When applying such conventional polishing pad in a chemical mechanical polishing procedure, the flatness of the substrate to be polished is not satisfactory, and the uniformity is raised. Therefore, the polishing particles in the slurry are remained on the surface of the substrate to be polished, and the surface of the substrate to be polished is scraped. If applying the conventional polishing pad in the manufacture of wafer, the scrapes on the surface of wafer affect the stability, and the subsequent procedures of litho or photo, development and etching. When stacking micro integrated circuits, the stability is diminished and the defective rate is raised. Thereby, the cost of manufacture is raised. Furthermore, when manufacturing the conventional polishing pad, volatile organic compounds are produced, and pollution is yielded.